BOSTON -- Police are on alert Thursday after two teenagers were stabbed on the Massachusetts Bay Transportation Authority's Orange Line as it approached Back Bay Station Wednesday night.

NewsCenter 5's Rhondella Richardson reported that T officials said they are working to assure passengers that safety is a top priority.

Officials said a fight started on board one of the trains and then spilled out onto the platform just before 8 p.m. on Wednesday. A 911 caller told police that a man stabbed two male teenagers several times, then ran up the escalator.

Officials said a 17-year-old boy was in critical condition at Boston Medical Center, while the other victim, a 19-year-old man, suffered injuries that were not life threatening. Both teens are from Boston's Jamaica Plain neighborhood.

Hundreds of passengers had to be directed to shuttle buses when the station closed for several hours after the attack.

"It makes me a little nervous especially when I am traveling with kids," said one commuter.

The attacker was described as a 15- to 17-year-old boy.

"There was a disturbance of some sort between one lone individual and a group of six to eight. It started downtown on the Orange Line and escalated. When the train arrived here at Back Bay, the lone individual took out a knife and stabbed two who were in that group of six to eight," said MBTA spokesman Joe Pesaturo.

Police were interviewing witnesses and reviewing surveillance tapes to see if they could identify the attacker on Thursday.

Passengers said so far, they are not impressed by the police work.

"You can't do it with a uniform and a camera. It is not going to work," one commuter said.

"I think the problem is they depend too much on technology. They need to communicate," another commuter said.

On Thursday, the T received approval to hire 34 new officers and promised more police visibility at every station.

"Sometimes in the afternoons, there is a lot of kids coming back from school and they can be a little bit wild. But generally, it is pretty good," said another commuter.

It was the second stabbing in only three weeks at the Back Bay Station. On Feb. 19, a West Roxbury teenager was stabbed nine times. With the help of surveillance cameras, police arrested three Boston high school students in connection with the attacks.

"There were 15 assaults up and down the Orange line -- all the way from Oak Grove to Forest Hills -- in a six-month period. During that time, 20 million people rode the Orange Line," Pesaturo said.